ROUTERA

Magnetic Effects of Electric Current

Class 10th Science Chapter Assertion and Reason

Magnetic Effects of Electric Current

  • Options:
    a) Both Assertion (A) and Reason (R) are true, and Reason (R) is the correct explanation of Assertion (A).
    b) Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of Assertion (A).
    c) Assertion (A) is true, but Reason (R) is false.
    d) Assertion (A) is false, but Reason (R) is true.

Question 1

Assertion (A): A current-carrying conductor produces a magnetic field around it.
Reason (R): The magnetic field is produced due to the movement of electric charges in the conductor.

  • Answer: a) Both Assertion (A) and Reason (R) are true, and Reason (R) is the correct explanation of Assertion (A).
  • Explanation: When electric current flows through a conductor, moving charges (electrons) create a magnetic field around it, as described by Ampère's law.

Question 2

Assertion (A): The direction of the magnetic field around a straight conductor can be determined using the right-hand thumb rule.
Reason (R): The thumb indicates the direction of current, while the curled fingers indicate the direction of the magnetic field.

  • Answer: a) Both Assertion (A) and Reason (R) are true, and Reason (R) is the correct explanation of Assertion (A).
  • Explanation: According to the right-hand thumb rule, if you point your thumb in the direction of the current, your curled fingers show the direction of the magnetic field lines around the conductor.

Question 3

Assertion (A): A solenoid is a long coil of wire.
Reason (R): A solenoid behaves like a bar magnet when an electric current passes through it.

  • Answer: a) Both Assertion (A) and Reason (R) are true, and Reason (R) is the correct explanation of Assertion (A).
  • Explanation: When current flows through a solenoid, it creates a magnetic field similar to that of a bar magnet, with distinct north and south poles.

Question 4

Assertion (A): The strength of the magnetic field inside a solenoid increases with an increase in current.
Reason (R): The magnetic field strength is directly proportional to the number of turns in the coil and the current flowing through it.

  • Answer: a) Both Assertion (A) and Reason (R) are true, and Reason (R) is the correct explanation of Assertion (A).
  • Explanation: The magnetic field strength in a solenoid is given by B=μ0×n×IB = \mu_0 \times n \times I, where BB is the magnetic field strength, nn is the number of turns per unit length, and II is the current. Therefore, increasing the current increases the magnetic field strength.

Question 5

Assertion (A): Electromagnets are used in many devices like cranes, relays, and motors.
Reason (R): Electromagnets can be turned on and off, providing control over magnetic fields.

  • Answer: a) Both Assertion (A) and Reason (R) are true, and Reason (R) is the correct explanation of Assertion (A).
  • Explanation: Electromagnets, made from coiled wire with current flowing through it, can be easily controlled by turning the current on or off, making them very useful in various applications.

Question 6

Assertion (A): The magnetic field inside a current-carrying solenoid is uniform.
Reason (R): The magnetic field lines are parallel and equally spaced inside the solenoid.

  • Answer: a) Both Assertion (A) and Reason (R) are true, and Reason (R) is the correct explanation of Assertion (A).
  • Explanation: Inside a solenoid, the magnetic field is uniform, which means that the strength of the field is consistent throughout its length, and the field lines are parallel and evenly spaced.

Question 7

Assertion (A): A current-carrying conductor experiences a force when placed in a magnetic field.
Reason (R): This force is due to the interaction between the magnetic field of the conductor and the external magnetic field.

  • Answer: a) Both Assertion (A) and Reason (R) are true, and Reason (R) is the correct explanation of Assertion (A).
  • Explanation: According to Fleming's left-hand rule, when a conductor carrying current is placed in an external magnetic field, a force acts on it due to the interaction between the two magnetic fields.

Question 8

Assertion (A): Fleming's left-hand rule is used to determine the direction of the force experienced by a current-carrying conductor in a magnetic field.
Reason (R): It states that if the thumb points in the direction of current and the forefinger in the direction of the magnetic field, then the middle finger points in the direction of the force.

  • Answer: a) Both Assertion (A) and Reason (R) are true, and Reason (R) is the correct explanation of Assertion (A).
  • Explanation: Fleming's left-hand rule provides a practical method to determine the direction of force acting on a current-carrying conductor in a magnetic field.

Question 9

Assertion (A): A magnetic field can induce current in a closed circuit.
Reason (R): This phenomenon is known as electromagnetic induction.

  • Answer: a) Both Assertion (A) and Reason (R) are true, and Reason (R) is the correct explanation of Assertion (A).
  • Explanation: Electromagnetic induction occurs when a changing magnetic field within a closed loop induces an electromotive force (emf), resulting in an electric current.

Question 10

Assertion (A): The direction of induced current in a circuit can be determined using Lenz's law.
Reason (R): Lenz's law states that the induced current will oppose the change in magnetic flux that produced it.

  • Answer: a) Both Assertion (A) and Reason (R) are true, and Reason (R) is the correct explanation of Assertion (A).
  • Explanation: Lenz's law helps determine the direction of induced current; it opposes any change in magnetic flux, thereby conserving energy.

Question 11

Assertion (A): A galvanometer can be used to measure current.
Reason (R): A galvanometer is an instrument that detects the presence of an electric current.

  • Answer: b) Assertion (A) is false, but Reason (R) is true.
  • Explanation: A galvanometer measures small currents, but it is not designed for measuring large currents directly. It can indicate the presence and direction of current flow.

Question 12

Assertion (A): The magnetic field produced by a current-carrying coil is stronger at its center than at its ends.
Reason (R): The magnetic field lines are concentrated at the center of the coil.

  • Answer: a) Both Assertion (A) and Reason (R) are true, and Reason (R) is the correct explanation of Assertion (A).
  • Explanation: The magnetic field is indeed stronger at the center of the coil due to the accumulation of magnetic field lines, making the field more intense there.

Question 13

Assertion (A): Magnetic field lines never intersect each other.
Reason (R): If magnetic field lines were to intersect, it would imply two different directions of the magnetic field at the same point.

  • Answer: a) Both Assertion (A) and Reason (R) are true, and Reason (R) is the correct explanation of Assertion (A).
  • Explanation: The intersection of magnetic field lines would indicate conflicting directions of the magnetic field, which is not possible. Therefore, they cannot intersect.

Question 14

Assertion (A): Magnetic field lines form closed loops.
Reason (R): The direction of magnetic field lines is from the north pole to the south pole.

  • Answer: a) Both Assertion (A) and Reason (R) are true, and Reason (R) is the correct explanation of Assertion (A).
  • Explanation: Magnetic field lines originate from the north pole and terminate at the south pole, creating closed loops that illustrate the magnetic field's continuous nature.

Question 15

Assertion (A): A current-carrying conductor in a magnetic field experiences maximum force when it is perpendicular to the field lines.
Reason (R): The force is given by the equation F=BILsin⁡θF = BIL \sin \theta, where θ\theta is the angle between the conductor and the magnetic field.

  • Answer: a) Both Assertion (A) and Reason (R) are true, and Reason (R) is the correct explanation of Assertion (A).
  • Explanation: The force experienced by the conductor is maximum when θ=90∘\theta = 90^\circ (perpendicular), leading to sin⁡θ=1\sin \theta = 1 in the equation, resulting in the greatest force.

Question 16

Assertion (A): The magnetic field of a bar magnet can be visualized using iron filings.
Reason (R): Iron filings align themselves along the magnetic field lines when sprinkled around the magnet.

  • Answer: a) Both Assertion (A) and Reason (R) are true, and Reason (R) is the correct explanation of Assertion (A).
  • Explanation: Iron filings show the shape and direction of the magnetic field lines when placed near a magnet, as they align along the lines of force created by the magnetic field.

Question 17

Assertion (A): A transformer works on the principle of electromagnetic induction.
Reason (R): It can step up or step down the voltage based on the number of turns in the primary and secondary coils.

  • Answer: a) Both Assertion (A) and Reason (R) are true, and Reason (R) is the correct explanation of Assertion (A).
  • Explanation: A transformer uses electromagnetic induction to convert alternating current (AC) voltages, stepping them up or down according to the turns ratio of the coils.

Question 18

Assertion (A): The earth's magnetic field protects the planet from solar winds.
Reason (R): The magnetic field deflects charged particles present in solar winds.

  • Answer: a) Both Assertion (A) and Reason (R) are true, and Reason (R) is the correct explanation of Assertion (A).
  • Explanation: The Earth's magnetic field acts as a shield against solar winds by deflecting charged particles, protecting the atmosphere and surface from harmful radiation.

Question 19

Assertion (A): The magnetic field of a solenoid can be increased by increasing the number of turns per unit length.
Reason (R): More turns increase the magnetic field strength as described by the formula B=μ0nIB = \mu_0 n I.

  • Answer: a) Both Assertion (A) and Reason (R) are true, and Reason (R) is the correct explanation of Assertion (A).
  • Explanation: The magnetic field strength BB in a solenoid increases with the number of turns nn and the current II, meaning more turns lead to a stronger magnetic field.

Question 20

Assertion (A): An electric motor converts electrical energy into mechanical energy.
Reason (R): It operates based on the interaction between the magnetic field and the current-carrying conductor.

  • Answer: a) Both Assertion (A) and Reason (R) are true, and Reason (R) is the correct explanation of Assertion (A).
  • Explanation: Electric motors function by utilizing the magnetic effects of current; the interaction between the magnetic field and current produces torque, converting electrical energy into mechanical work.